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Rewrite the AttachmentsClassLoader to avoid temporary file copies and fix the overlap check.

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Throw a specialised exception that lists missing exceptions during deserialisation, so the dependency resolution code can access it (coming up).
This commit is contained in:
Mike Hearn 2016-04-14 17:51:53 +02:00
parent 7e9cbaa36e
commit e91c46f045
5 changed files with 152 additions and 96 deletions
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3
core/build.gradle
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@ -28,6 +28,9 @@ dependencies {
compile "org.jetbrains.kotlin:kotlin-reflect:$kotlin_version"
compile "org.jetbrains.kotlin:kotlin-test:$kotlin_version"
// Thread safety annotations
compile "com.google.code.findbugs:jsr305:3.0.1"
// SLF4J: Logging framework.
compile "org.slf4j:slf4j-jdk14:1.7.13"

121
core/src/main/kotlin/core/node/AttachmentsClassLoader.kt
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@ -1,67 +1,106 @@
package core.node
import core.Attachment
import java.io.Closeable
import java.io.File
import java.io.FileOutputStream
import core.crypto.SecureHash
import java.io.ByteArrayInputStream
import java.io.ByteArrayOutputStream
import java.io.FileNotFoundException
import java.io.InputStream
import java.net.URL
import java.net.URLClassLoader
import java.net.URLConnection
import java.net.URLStreamHandler
import java.security.CodeSigner
import java.security.CodeSource
import java.security.SecureClassLoader
import java.util.*
import java.util.jar.JarEntry
class OverlappingAttachments : Exception()
/**
* A custom ClassLoader for creating contracts distributed as attachments and for contracts to
* access attachments.
* A custom ClassLoader that knows how to load classes from a set of attachments. The attachments themselves only
* need to provide JAR streams, and so could be fetched from a database, local disk, etc. Constructing an
* AttachmentsClassLoader is somewhat expensive, as every attachment is scanned to ensure that there are no overlapping
* file paths.
*/
class AttachmentsClassLoader private constructor(val tmpFiles: List<File>)
: URLClassLoader(tmpFiles.map { URL("file", "", it.toString()) }.toTypedArray()), Closeable {
class AttachmentsClassLoader(attachments: List<Attachment>) : SecureClassLoader() {
private val pathsToAttachments = HashMap<String, Attachment>()
private val idsToAttachments = HashMap<SecureHash, Attachment>()
override fun close() {
super.close()
class OverlappingAttachments(val path: String) : Exception() {
override fun toString() = "Multiple attachments define a file at path $path"
}
for (file in tmpFiles) {
file.delete()
init {
for (attachment in attachments) {
attachment.openAsJAR().use { jar ->
while (true) {
val entry = jar.nextJarEntry ?: break
// We already verified that paths are not strange/game playing when we inserted the attachment
// into the storage service. So we don't need to repeat it here.
//
// We forbid files that differ only in case to avoid issues for Windows/Mac developers where the
// filesystem tries to be case insensitive. This may break developers who attempt to use ProGuard.
//
// TODO: Do we need extra overlap checks?
val path = entry.name.toLowerCase()
if (path in pathsToAttachments)
throw OverlappingAttachments(path)
pathsToAttachments[path] = attachment
}
}
idsToAttachments[attachment.id] = attachment
}
}
override fun loadClass(name: String?, resolve: Boolean): Class<*>? {
return super.loadClass(name, resolve)
// Example: attachment://0b4fc1327f3bbebf1bfe98330ea402ae035936c3cb6da9bd3e26eeaa9584e74d/some/file.txt
//
// We have to provide a fake stream handler to satisfy the URL class that the scheme is known. But it's not
// a real scheme and we don't register it. It's just here to ensure that there aren't codepaths that could
// lead to data loading that we don't control right here in this class (URLs can have evil security properties!)
private val fakeStreamHandler = object : URLStreamHandler() {
override fun openConnection(u: URL?): URLConnection? {
throw UnsupportedOperationException()
}
}
companion object {
fun create(streams: List<Attachment>): AttachmentsClassLoader {
private fun Attachment.toURL(path: String?) = URL(null, "attachment://$id/" + (path ?: ""), fakeStreamHandler)
validate(streams)
var tmpFiles = streams.map {
var filename = File.createTempFile("jar", "")
it.open().use {
str ->
FileOutputStream(filename).use { str.copyTo(it) }
override fun findClass(name: String): Class<*> {
val path = name.replace('.', '/').toLowerCase() + ".class"
val attachment = pathsToAttachments[path] ?: throw ClassNotFoundException(name)
val stream = ByteArrayOutputStream()
try {
attachment.extractFile(path, stream)
} catch(e: FileNotFoundException) {
throw ClassNotFoundException(name)
}
filename
val bytes = stream.toByteArray()
// We don't attempt to propagate signatures from the JAR into the codesource, because our sandbox does not
// depend on external policy files to specify what it can do, so the data wouldn't be useful.
val codesource = CodeSource(attachment.toURL(null), emptyArray<CodeSigner>())
// TODO: Define an empty ProtectionDomain to start enforcing the standard Java sandbox.
// The standard Java sandbox is insufficient for our needs and a much more sophisticated sandboxing
// ClassLoader will appear here in future, but it can't hurt to use the default one too: defence in depth!
return defineClass(name, bytes, 0, bytes.size, codesource)
}
return AttachmentsClassLoader(tmpFiles)
override fun findResource(name: String): URL? {
val attachment = pathsToAttachments[name.toLowerCase()] ?: return null
return attachment.toURL(name)
}
private fun validate(streams: List<Attachment>) {
val set = HashSet<String>()
val jars = streams.map { it.openAsJAR() }
for (jar in jars) {
var entry: JarEntry = jar.nextJarEntry ?: continue
if (set.add(entry.name) == false) {
throw OverlappingAttachments()
override fun getResourceAsStream(name: String): InputStream? {
val url = getResource(name) ?: return null // May check parent classloaders, for example.
if (url.protocol != "attachment") return null
val attachment = idsToAttachments[SecureHash.parse(url.host)] ?: return null
val path = url.path?.substring(1) ?: return null // Chop off the leading slash.
try {
val stream = ByteArrayOutputStream()
attachment.extractFile(path, stream)
return ByteArrayInputStream(stream.toByteArray())
} catch(e: FileNotFoundException) {
return null
}
}
}
}
}

77
core/src/main/kotlin/core/serialization/Kryo.kt
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@ -12,6 +12,7 @@ import core.*
import core.crypto.SecureHash
import core.crypto.generateKeyPair
import core.crypto.sha256
import core.node.AttachmentsClassLoader
import core.node.services.AttachmentStorage
import de.javakaffee.kryoserializers.ArraysAsListSerializer
import org.objenesis.strategy.StdInstantiatorStrategy
@ -21,6 +22,7 @@ import java.nio.file.Files
import java.nio.file.Path
import java.time.Instant
import java.util.*
import javax.annotation.concurrent.ThreadSafe
import kotlin.reflect.*
import kotlin.reflect.jvm.javaType
@ -189,6 +191,51 @@ inline fun <T> Kryo.useClassLoader(cl: ClassLoader, body: () -> T) : T {
}
}
/** Thrown during deserialisation to indicate that an attachment needed to construct the [WireTransaction] is not found */
class MissingAttachmentsException(val ids: List<SecureHash>) : Exception()
/** A serialisation engine that knows how to deserialise code inside a sandbox */
@ThreadSafe
object WireTransactionSerializer : Serializer<WireTransaction>() {
override fun write(kryo: Kryo, output: Output, obj: WireTransaction) {
kryo.writeClassAndObject(output, obj.inputs)
kryo.writeClassAndObject(output, obj.attachments)
kryo.writeClassAndObject(output, obj.outputs)
kryo.writeClassAndObject(output, obj.commands)
}
@Suppress("UNCHECKED_CAST")
override fun read(kryo: Kryo, input: Input, type: Class<WireTransaction>): WireTransaction {
val inputs = kryo.readClassAndObject(input) as List<StateRef>
val attachmentHashes = kryo.readClassAndObject(input) as List<SecureHash>
// If we're deserialising in the sandbox context, we use our special attachments classloader.
// Otherwise we just assume the code we need is on the classpath already.
val attachmentStorage = kryo.attachmentStorage
val classLoader = if (attachmentStorage != null) {
val missing = ArrayList<SecureHash>()
val attachments = ArrayList<Attachment>()
for (id in attachmentHashes) {
val attachment = attachmentStorage.openAttachment(id)
if (attachment == null)
missing += id
else
attachments += attachment
}
if (missing.isNotEmpty())
throw MissingAttachmentsException(missing)
AttachmentsClassLoader(attachments)
} else javaClass.classLoader
kryo.useClassLoader(classLoader) {
val outputs = kryo.readClassAndObject(input) as List<ContractState>
val commands = kryo.readClassAndObject(input) as List<Command>
return WireTransaction(inputs, attachmentHashes, outputs, commands)
}
}
}
fun createKryo(k: Kryo = Kryo()): Kryo {
return k.apply {
// Allow any class to be deserialized (this is insecure but for prototyping we don't care)
@ -211,35 +258,7 @@ fun createKryo(k: Kryo = Kryo()): Kryo {
}
})
register(WireTransaction::class.java, object : Serializer<WireTransaction>() {
override fun write(kryo: Kryo, output: Output, obj: WireTransaction) {
kryo.writeClassAndObject( output, obj.inputs )
kryo.writeClassAndObject( output, obj.attachments )
kryo.writeClassAndObject( output, obj.outputs )
kryo.writeClassAndObject( output, obj.commands )
}
@Suppress("UNCHECKED_CAST")
override fun read(kryo: Kryo, input: Input, type: Class<WireTransaction>): WireTransaction {
var inputs = kryo.readClassAndObject( input ) as List<StateRef>
var attachments = kryo.readClassAndObject( input ) as List<SecureHash>
val attachmentStorage = kryo.attachmentStorage
// .filterNotNull in order for TwoPartyTradeProtocolTests.checkDependenciesOfSaleAssetAreResolved test to run
val classLoader = core.node.AttachmentsClassLoader.create( attachments.map { attachmentStorage?.openAttachment(it) }.filterNotNull() )
kryo.useClassLoader(classLoader) {
var outputs = kryo.readClassAndObject(input) as List<ContractState>
var commands = kryo.readClassAndObject(input) as List<Command>
return WireTransaction(inputs, attachments, outputs, commands)
}
}
})
register(WireTransaction::class.java, WireTransactionSerializer)
// Some things where the JRE provides an efficient custom serialisation.
val ser = JavaSerializer()

2
src/main/kotlin/core/node/services/NodeAttachmentService.kt
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@ -144,7 +144,7 @@ class NodeAttachmentService(val storePath: Path, val metrics: MetricRegistry) :
val cursor = stream.nextJarEntry ?: break
val entryPath = Paths.get(cursor.name)
// Security check to stop zips trying to escape their rightful place.
if (entryPath.isAbsolute || entryPath.normalize() != entryPath)
if (entryPath.isAbsolute || entryPath.normalize() != entryPath || '\\' in cursor.name)
throw IllegalArgumentException("Path is either absolute or non-normalised: $entryPath")
}
}

35
src/test/kotlin/core/node/ClassLoaderTests.kt → src/test/kotlin/core/node/AttachmentClassLoaderTests.kt
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@ -1,15 +1,11 @@
package core.node
import com.esotericsoftware.kryo.KryoException
import contracts.DUMMY_PROGRAM_ID
import contracts.DummyContract
import core.*
import core.crypto.SecureHash
import core.node.services.AttachmentStorage
import core.serialization.attachmentStorage
import core.serialization.createKryo
import core.serialization.deserialize
import core.serialization.serialize
import core.serialization.*
import core.testutils.MEGA_CORP
import org.apache.commons.io.IOUtils
import org.junit.Test
@ -28,8 +24,8 @@ interface DummyContractBackdoor {
fun inspectState(state: ContractState): Int
}
class ClassLoaderTests {
val ISOLATED_CONTRACTS_JAR_PATH = ClassLoaderTests::class.java.getResource("isolated.jar")
class AttachmentClassLoaderTests {
val ISOLATED_CONTRACTS_JAR_PATH = AttachmentClassLoaderTests::class.java.getResource("isolated.jar")
fun importJar(storage: AttachmentStorage) = ISOLATED_CONTRACTS_JAR_PATH.openStream().use { storage.importAttachment(it) }
@ -72,8 +68,8 @@ class ClassLoaderTests {
val att1 = storage.importAttachment(ByteArrayInputStream(fakeAttachment("file.txt", "some data")))
val att2 = storage.importAttachment(ByteArrayInputStream(fakeAttachment("file.txt", "some other data")))
assertFailsWith(OverlappingAttachments::class) {
AttachmentsClassLoader.create(arrayOf(att0, att1, att2).map { storage.openAttachment(it)!! })
assertFailsWith(AttachmentsClassLoader.OverlappingAttachments::class) {
AttachmentsClassLoader(arrayOf(att0, att1, att2).map { storage.openAttachment(it)!! })
}
}
@ -85,11 +81,10 @@ class ClassLoaderTests {
val att1 = storage.importAttachment(ByteArrayInputStream(fakeAttachment("file1.txt", "some data")))
val att2 = storage.importAttachment(ByteArrayInputStream(fakeAttachment("file2.txt", "some other data")))
AttachmentsClassLoader.create(arrayOf(att0, att1, att2).map { storage.openAttachment(it)!! }).use {
val txt = IOUtils.toString(it.getResourceAsStream("file1.txt"))
val cl = AttachmentsClassLoader(arrayOf(att0, att1, att2).map { storage.openAttachment(it)!! })
val txt = IOUtils.toString(cl.getResourceAsStream("file1.txt"))
assertEquals("some data", txt)
}
}
@Test
fun `loading class AnotherDummyContract`() {
@ -99,12 +94,11 @@ class ClassLoaderTests {
val att1 = storage.importAttachment(ByteArrayInputStream(fakeAttachment("file1.txt", "some data")))
val att2 = storage.importAttachment(ByteArrayInputStream(fakeAttachment("file2.txt", "some other data")))
AttachmentsClassLoader.create(arrayOf(att0, att1, att2).map { storage.openAttachment(it)!! }).use {
val contractClass = Class.forName("contracts.isolated.AnotherDummyContract", true, it)
val cl = AttachmentsClassLoader(arrayOf(att0, att1, att2).map { storage.openAttachment(it)!! })
val contractClass = Class.forName("contracts.isolated.AnotherDummyContract", true, cl)
val contract = contractClass.newInstance() as Contract
assertEquals(SecureHash.sha256("https://anotherdummy.org"), contract.legalContractReference)
}
}
/**
@ -146,10 +140,10 @@ class ClassLoaderTests {
val att1 = storage.importAttachment(ByteArrayInputStream(fakeAttachment("file1.txt", "some data")))
val att2 = storage.importAttachment(ByteArrayInputStream(fakeAttachment("file2.txt", "some other data")))
val clsLoader = AttachmentsClassLoader.create(arrayOf(att0, att1, att2).map { storage.openAttachment(it)!! })
val cl = AttachmentsClassLoader(arrayOf(att0, att1, att2).map { storage.openAttachment(it)!! })
val kryo = createKryo()
kryo.classLoader = clsLoader
kryo.classLoader = cl
val state2 = bytes.deserialize(kryo, true)
@ -173,10 +167,10 @@ class ClassLoaderTests {
val att1 = storage.importAttachment(ByteArrayInputStream(fakeAttachment("file1.txt", "some data")))
val att2 = storage.importAttachment(ByteArrayInputStream(fakeAttachment("file2.txt", "some other data")))
val clsLoader = AttachmentsClassLoader.create(arrayOf(att0, att1, att2).map { storage.openAttachment(it)!! })
val cl = AttachmentsClassLoader(arrayOf(att0, att1, att2).map { storage.openAttachment(it)!! })
val kryo = createKryo()
kryo.classLoader = clsLoader
kryo.classLoader = cl
val state2 = bytes.deserialize(kryo)
@ -251,8 +245,9 @@ class ClassLoaderTests {
// use empty attachmentStorage
kryo2.attachmentStorage = MockAttachmentStorage()
assertFailsWith(KryoException::class) {
val e = assertFailsWith(MissingAttachmentsException::class) {
bytes.deserialize(kryo2)
}
assertEquals(attachmentRef, e.ids.single())
}
}